On Wed, Jan 31, 2018 at 01:28:43PM +0100, Linus Walleij wrote:

On Mon, Jan 29, 2018 at 5:09 PM, Dave Martin [off-list ref] wrote:

quoted

Commit 9b96fbacda34 ("serial: PL011: clear pending interrupts")
clears the RX and receive timeout interrupts on pl011 startup, to
avoid a screaming-interrupt scenario that can occur when the
firmware or bootloader leaves these interrupts spuriously
asserted.

It looks OK to me.

You mean, the original patch?

I think there is a real potential bug here for SBSA UART, but I also
haven't been able to reproduce it on hardware.

I'm not sure whether it can happen on a real pl011, given that the
driver turns the FIFOs off and on etc.  That may get us back into a
sane state.  On the SBSA UART this does nothing: the SBSA UART
cannot be reset or disabled directly IIRC.

I could never reproduce this issue myself, it was just reported by
Chanho, and we came up with this fix. AFAICR it was working fine
on ARM reference designs and my ST-Ericsson platforms before
and after.

I do not remember what hardware Chanho was seeing this problem
on, but let's loop in Chanho and ask.

OK, thanks
---Dave